@StompyRobot @graydon @cstross @david_chisnall @linuxgnome @ChrisMayLA6 In my casual understanding the all in gains of back side power are still 10-15% marginal, the transistors are what they are and reading a memory is still firing off a lot of sense amps, and most of the area in lithography these days is in RAMs. The amount of time and energy it takes to access an address in SRAM and DRAM arrays is no longer scaling and hasn't for a while.
pJ/bit for transceivers is the only thing that has been scaling nicely tanks to building in a lot of advanced FEC etc, now two bits/baud on the wire, but the analog PHY is not any smaller in PCIe gen 6 vs gen 5. It costs same energy scale to launch a bit from the edge to another die than to cross the die you are on, almost, which is a very new thing vs 10-15 years ago.... but you spend a ton of area in PHY to do that, are not switching really and in the end you still are using Maxwell to tickle electrons on a skinny wire. Your typical N5 ASIC (non-CPU) is running the global system fabric with core clocks around 500MHz-1GHz on the high end. Faster clocks thicker wires more power; all the benefits of smaller transistors are mainly nowadays because the bits don't need to move as far.
Quantum computers don't apply to many real world problems, just maybe simulating some quantum physics at small scale and breaking traditional asymmetric crypto. On the crudest level: the problem has to fit into a very small number of bits so you are not doing the weather with them.
For the problems they can do, the number of physical qubits to implement a logical qubit is a substantial multiplier and the error correction you must do is another substantial multiplier on quantum gate depth you need to get anywhere. Also there is a brutal threshold effect in the quantum error correction. It's not Robert Goddard now Saturn V later, it is not even bottle rocket now vs New Horizons later. These are tightly coupled physical systems where (to me) it isn't clear you can get to the scale of isolation you need vs the noisy physical world. There is a lot more math physics and engineering needed.
All in my opinion.
